public class Text5 {
    //852.山脉数组的峰顶索引
    public int peakIndexInMountainArray(int[] arr) {
        int left = 1, right = arr.length - 1;

        while(left < right){
            int mid = left + (right - left + 1)/2;
            if(arr[mid] > arr[mid-1]){
                left = mid ;
            } else {
                right = mid - 1;
            }
        }

        return left;
    }
}
